<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div class="btn-group dropup">
    <button type="button" class="btn btn-default">Dropup</button>
    <button type="button" class="btn btn-default dropdown-toggle" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
        <span class="caret"></span>
        <span class="sr-only">Toggle Dropdown</span>
    </button>
    <ul class="dropdown-menu">
        <!-- Dropdown menu links -->
    </ul>
</div>

</body>
</html>